Have you tried the brand oVertone (color conditioner)?

I'm looking for some insights into the Honey or Espresso color for brown hair. I'm interested in the conditioning and coloring properties of oVertone, but don't want to go with a vibrant or pastel color not found on a natural head of hair. If you've used oVertone, what did you think about it? Bonus points for brunettes (with some gray) who used either the Espresso or Honey color. How did it come out? Did it cover any of your gray (even temporarily)? Thanks for any insights you may have!